Working pressure is the number operators argue about most when they compare steam cleaning machines, and it is also the one most often quoted without context. A catalogue line may show a pressure figure, but that figure says little about whether the machine suits a fixed bay or a vehicle that has to move between sites. Before comparing a fixed steam cleaning machine with a mobile unit, operators should work out where the pressure figure comes from, how it behaves over a full shift, and what it does to the cleaning task they actually run.
What the pressure figure on a data sheet really describes
Most steam machines list a vapour pressure measured at the boiler or generator, not the pressure arriving at the nozzle. Distance, hose length, internal diameter, kinks and nozzle wear all reduce what the operator feels in the hand. On the PowerDe HW02 steam cleaner, for example, the published parameters give a vapour pressure of 0.8 MPa together with a steam temperature of 160°C and 6 kW of heating power. Those three values need to be read as a set. The pressure pushes the steam out; the temperature carries the thermal energy that softens grease; the heating power decides how quickly the unit replaces the energy it is losing.
A practical comparison therefore asks three questions rather than one. First, is the quoted pressure a boiler value or a delivery value? Second, does the machine hold that pressure while steam is flowing, or only when the trigger is closed? Third, does the water tank and heating capacity keep the pressure stable through a full job? When operators compare on those terms, a single headline number stops being decisive.
How fixed units hold pressure through a long job
A fixed machine sits on one floor, plugs into mains power, and draws water from a supply or a tank large enough that refilling does not interrupt work. The HW02 is described as a 220 V unit with an 80 L SUS304 tank, tap-water inlet and dry or wet steam selection, alongside an integrated vacuum function. That combination matters for pressure comparison in a specific way: a large tank and continuous mains power let the generator recover between bursts, so the pressure the operator sets in the morning is close to the pressure still available at the end of the day.
Fixed installations also allow longer hose runs and heavier accessories without the operator carrying the weight. The trade-off is that the cleaning has to come to the machine. Bays, marked work areas, cable routes and drainage all need planning, and the machine cannot follow a vehicle that parks somewhere else. Where the site layout supports it, this is the reason fixed units generally deliver the more stable pressure of the two options.
What mobile units trade away, and what they gain
Mobile machines move the pressure source to the job instead. PowerDe's driving-style models, such as the PWD01 and PWD02 listed in the cleaning equipment series, are described as mobile active-water machines offering dry steam, wet steam and hot water modes, aimed at indoor garages and narrow outdoor parking spaces. Battery versions carry their own power supply, and the same product family also covers hand-pushed machines such as the HMW3, which runs on a 48 V battery with a 50 L clean water tank and a hand-push mode of movement.
On a mobile unit the limiting factor is stored energy, not the wall socket. Battery capacity and tank volume set how long pressure can be sustained before charging or refilling, and the generator has to be small enough to travel. That does not make the pressure inadequate for the intended work; it makes the duty cycle shorter and more finite. Operators comparing mobile options should therefore ask for run time per charge, refill intervals and how the machine behaves as the battery declines, not just for a peak pressure figure. Mobile reach is the gain: no bay to build, no cable route to plan, and the machine can cover a yard, a row of parked vehicles, or several floors.
A comparison framework operators can apply on site
A short, structured test on the actual site settles the question faster than reading specifications. The following checks cover the points that decide which pressure behaviour suits the operation:
- Map the distance. Count the metres between the machine position and the furthest surface to be cleaned. Fixed units tolerate long hose runs; a mobile unit shortens that distance instead.
- Time one full cycle. Run the heaviest job of the day and record how long the machine holds usable pressure, then how long recovery takes. Compare fixed and mobile on the same task.
- Check the tank and power source together. A tank that runs dry or a battery that fades will show up as a drop in steam output well before the data sheet pressure becomes relevant.
- Match the mode to the soiling. Dry steam suits light surface soiling and sanitising work where low moisture matters. Wet steam and hot water modes carry more water into the task, which helps with heavier deposits.
- Inspect the delivery path. Nozzle condition, hose length and fittings change delivered pressure more than most operators expect, and the same wear applies to both fixed and mobile setups.
Choosing between the two by workload, not by numbers
For operations concentrated in one area, with a steady flow of vehicles or equipment passing through the same point, a fixed unit is usually the more consistent answer on working pressure. Continuous power and a larger tank mean the machine can be run hard for hours, and the pressure the operator starts with is the pressure they finish with. For work spread across a site, or for operations that cannot dedicate floor space to a bay, a mobile machine removes the layout problem and accepts a shorter duty cycle in exchange.
Many operators end up running both: a fixed machine for the high-volume area and a mobile unit for everything outside it. If you are specifying equipment for that kind of mixed setup, it is worth confirming the pressure, temperature and heating figures for each model directly, along with protection features and tank capacity, so the two halves of the operation are matched to their actual workload.
